I usually refrain from entering these threads, but I feel compelled to say a few things. Please pardon me if any of it comes off sounding harsh.
In my mind, these young girls are not "choosing motherhood." They are choosing their unrealistic and highly idealized misperception of what life as a single teenage girl with a baby happens to be like.
Don't get me wrong. I am a father, and my wife and I are about to have our second child any day now. Our children have been a wonderfully encriching part of our lives. My wife is now a stay-at-home mom by her own choice, although she is smart enough and talented enough to pursue any career that she may have desired. However, we waited to have children until we were married, committed to each other, and felt that our relationship had enough time to consolidate that we could offer our children a family with a warm and strong marriage at it's core.
In my career, I have seen a lot of these young women, nay, mere girls who have "chosen" motherhood, and I think if most of them really knew what they were getting into, they would certainly think otherwise.
It is sad that in our world young girls are taught to see this as "choosing independence." What they are choosing is most likely a life on wellfare. What they also fail to consider entirely is the situation into which they are bringing the young child.
Becoming a parent should not be a selfish choice, because being a parent requires a degree of unselfishness greater than any other role in life. Parenthood is for adults who are ready to make a committment to the next generation. Parenthood is for mature individuals who are able of conceptualizing what it truly entails. Parenthood is a lifestyle, a highly rewarding one, but one that requires a great deal of focus on someone other than the self.
Having a child to be independent is, quite simply, a total oxymoron! You cannot be "independent" (the vaunted golden idol of many) when you have a small human being that is totally dependent on you for it's very survival.
Independence requires hard work, not mere fertility. And ultimately, independence may be a red herring, because human connection is an innate human need (see all of the research on attachment for an example). Interdependence is necessary and healthy, given that it does not lead to an extreme and fused style of relating to other people.
I feel very sorry for these young girls, for how they have been misguided in this way. However, my deepest sympthies go to their children.